Nervous system part 2 Flashcards
Norepinephrine and epinephrine
Epinephrine and norepinephrine are very similar neurotransmitters and hormones. While epinephrine has slightly more of an effect on your heart, norepinephrine has more of an effect on your blood vessels. Both play a role in your body’s natural fight-or-flight response to stress.
Norepinephrine
A hormone (which you might know as adrenaline). It has been linked to mood, memory, and stress.
Serotonin
“calming” chemical, mood modifier, linked to depression and appetite management, sleep, memory, and, most recently, decision-making behaviours.
Dopamine
Dopamine: “pleasure chemical” released when mammals receive a reward in response to their behaviour.
Low levels of serotonin may cause what?
anxiety or depression
Which neurotransmitter is primarily associated with feelings of pleasure and reward?
Dopamine
Which neurotransmitter plays a key role in regulating mood, sleep, and appetite?
Serotonin
Neurodegenerative Disorders
Neurodegenerative disorders are primarily characterized by neuron loss.
The most common neurodegenerative disorders include Alzheimer’s and Parkinson’s disease.
Although there are several medicines currently approved for managing neurodegenerative disorders, a large majority of them only help with associated symptoms.
Alzheimer’s Disease (AD)
Alzheimer’s disease affects brain function, memory, and behaviour.
Alzheimer’s is the most common cause of dementia, a general term for memory loss and other cognitive abilities serious enough to interfere with daily life.
In most people with Alzheimer’s, symptoms first appear later in life.
Cerebral Palsy (CP)
- Cerebral palsy affects the cerebral motor cortex.
- This is the part of the brain that directs muscle movement.
- In fact, the first part of the name, cerebral, means having to do with the brain.
The second part, palsy, means weakness or problems with using the muscles.
CP is caused by abnormal/irregular brain development or damage to the developing brain in the parts of the brain that control movement. It affects a person’s ability to control his or her muscles.
This usually happens before a child is born, but it can occur at birth or in early infancy, when the brain is still developing. In many cases the exact cause of cerebral palsy is not known.
Most individuals with cerebral palsy are born with it (85-90%), but those that acquire it in early childhood typically get it from head injury, environmental factors, and infections.
Multiple Sclerosis
an autoimmune disorder
leading to demyelination of nerve cells and disruption of nerve impulses
Types of Stroke
Ischemic and Hemorrhagic
Ischemic strokes
These are strokes caused by blockage of an artery (or, in rare instances, a vein). About 87% of all strokes are ischemic. Ischemic stroke is by far the most common type of stroke, accounting for a large majority of strokes.
Hemorrhagic stroke.
These are strokes caused by bleeding. About 13% of all strokes are hemorrhagic.
Anoxia vs Hypoxia
Anoxia
Lack of oxygen
Hypoxia
Low oxygen
Two types of ischemic strokes
Thrombotic
Embolic
Thrombotic stroke
occurs when a blood clot, called a thrombus, blocks an artery to the brain and stops blood flow.
embolic stroke
caused by a blood clot that forms elsewhere in the body (embolus) and travels through the bloodstream to the brain.
often result from heart disease or heart surgery and occur rapidly and without any warning signs.
Bell’s palsy
A condition that causes sudden weakness in the muscles on one side of the face.
Often the weakness is short-term (temporary) and improves over weeks.
The weakness makes half of the face appear to droop.
Smiles are one-sided, and the eye on the affected side is hard to close.
Amyotrophic Lateral Sclerosis
Amyotrophic lateral sclerosis is a fatal type of motor neuron disease.
It is characterized by progressive degeneration of nerve cells in the spinal cord and brain.
It’s often called Lou Gehrig’s disease, after a famous baseball player who died from the disease.
MS vs ALS
MS damages the myelin sheaths in the brain and spinal cord which prohibits them from sending out signals to motor neurons in the body.
ALS causes the death of the motor neurons.
Which of the following is a genetic (inherited) disease that causes nerve cells (neurons) in the brain to gradually waste away (break down) and die?
Huntington’s disease
Which disease or disorder results when the neurons in the brain that produce dopamine die?
Parkinson’s disease
A common neurological disorder where a blood clot results in improper oxygen delivery to the brain is known as:
Stroke
Multiple sclerosis (MS) is characterized by:
Demyelination of nerve fibers
Alzheimer’s disease primarily affects which part of the brain?
Hippocampus
Hippocampus
The hippocampus is embedded deep in the temporal lobe.
It has a major role in learning and memory.
The 5 basic human senses
Sight, smell, hearing, taste, and touch
The sensing organs associated with each sense send information to the brain to help us understand the world around us.
Stimuli
changes in one’s environment.
Receptor
groups of cells found on our sensory organs that detect changes in the environment.
Sensory organs
he organs that make our senses possible; our eyes, ears, nose, tongue, and skin.
Sensory organs
Sensory Organs
The tongue
The nose
The eye
The ear
The skin
The tongue
The tongue is a muscular organ.
It is the sensory organ for the sense of taste.
The taste buds are the sensory receptors for taste.
Taste buds are found in the grooves on the surface of the tongue.
A taste bud can detect the following flavours:
sweet
salty
sour
bitter
umami (savoury)
Taste buds
Each taste bud contains 50 to 100 taste cells, which contain molecules, known as receptors, that can detect each type of taste.
Taste
The flavour molecules, dissolved in the saliva, come into contact with the taste buds and stimulate the receptor cells.
The receptor cells transform this stimulus into a nerve signal that is transmitted to the brain.
In addition to the 5 flavours, the tongue can also perceive the following stimuli:
In addition to the 5 flavours, the tongue can also perceive the following stimuli:
Temperature
Pressure
Pain
Anosmia
Anosmia is the partial or full loss of smell.
It can be a temporary or permanent condition.
You can partially or completely lose your sense of smell when the mucus membranes in your nose are irritated or obstructed such as when you have a severe cold or a sinus infection, for example.
The nose
The nose is the sensory organ for the sense of smell.
The part of the nose involved in smelling is the nasal cavity.
The part of the brain involved in smelling is the olfactory bulb.
Olfaction
The nose is the sensory organ for the sense of smell.
The part of the nose involved in smelling is the nasal cavity.
The part of the brain involved in smelling is the olfactory bulb.
OLfaction
Olfaction – sense of smell
How do we smell
Air (containing volatiles, smell molecules) passes into the nasal cavity which contains olfactory receptor cells.
These receptors transform odours (smells) into nerve impulses and transmit these nerve impulses to the olfactory bulb in the brain.
The olfactory bulb sends the nerve impulses to another part of the brain, the olfactory cortex, that decodes smell.
The olfactory epithelium
The olfactory epithelium contains the sensory receptor cells for smell.
PATH
Nostril → nasal cavity → olfactory receptor cells → olfactory bulb
Why is it difficult to smell a flower when a person has a cold and “blocked nose”?
There is mucous covering the receptor cells so odour molecules (volatiles) can’t reach the receptor cells.
The Sclera
The sclera, or white of the eye, is strong tissue that wraps around your eyeball.
It helps maintain your eye’s shape and protects it from injury.
Iris
Provides colour and adjusts the amount of light to fall on the retina.
It dilates (widens) to allow more light in through the pupil
It contracts (narrows) to allow less light in through the pupil
The cornea
A transparent outer layer which allows light to enter the eye
Its curvature bends the light into the eye through the pupil
Lens
Focuses light directly onto the retina
Retina
Located at the back of the eye
Contains light receptor cells that transform light into nerve impulses that are then transmitted to the brain by the optic nerve
Rods and cones
Photoreceptors located in the retina.
The fovea and macula
The macula is the center portion of the retina that produces even sharper vision with its rods and cones.
The fovea is the pit inside the macula with only cones, so vision can be at its sharpest.
The optic disc
There are no light sensitive rods or cones to respond to a light stimulus at this point.
This causes a break in the visual field called “the blind spot”.
How do we see
When light hits the retina (a light-sensitive layer of tissue at the back of the eye), special cells called photoreceptors turn the light into electrical signals.
These electrical signals travel from the retina through the optic nerve to the brain.
Then the brain turns the signals into the images you see.
Which of the following is the correct order for the path of light as it enters the eye?
Cornea, pupil, lens
Which structure of the eye focuses light onto the retina?
Lens
On a very bright and sunny day, Jamal goes outside to play. How will his eyes adjust to the extra amount of light?
Jamal’s irises will contract (pupil gets smaller) so less light will enter his eyes.
Auditory canal
Canal that funnels outside sounds towards the eardrum
Eardrum
A thin membrane that transmits sound waves to the ossicles
Ossicles
3 small bones which transfer the vibrations from the eardrum to the cochlea
Semi circular canal
3 fluid filled semicircular canals that help maintain balance. The fluid’s movement in each semi circular canal determines the heads position in space
Cochlea
Snail like structure which transforms vibrations from the ossicles into electrical nerve impulses via sensory receptors, called hair cells, found inside the cochlea
The semi circular canals
When the fluid moves (due to body movements), the hair cells vibrate and send a message to the brain.
The brain then processes the information and decides how to keep the body balanced.
Rods
Rods are more numerous and good for detecting light in general.
Cones
Cones are concentrated near the fovea, responsible for colour vision, and able to adapt quickly to changes in light.
Name the structure of the ear where the sound vibrations are transformed into nerve impulses:
A) Ossicles
B) Semicircular canals
C) Cochlea
D) Eardrum
The skin
The sensory receptors found in the skin are activated by feelings of (stimuli such as):
Pressure
Temperature
Pain
These receptor cells transform the sensed stimulus into nerve impulses.
The nerve impulses are then transmitted by sensory neurons to the brain.
Mechanoreceptors
Respond to pressure and movements
Most mechanoreceptors are found in the skin and are needed for the sense of touch.
Mechanoreceptors are also found in the inner ear, where they are needed for the senses of hearing and balance
Chemoreceptors
Respond to chemicals (like those in what we eat)
Thermoreceptors
Respond to changes in temperature
They are found mostly in the skin
They detect temperatures that are above or below body temperature (37oC).
Photoreceptors
Detect and respond to light
Mostly found in the eyes.
Needed for the sense of vision.
Nociceptors
Detect and respond to pain
